CN219036404U

CN219036404U - Motor vehicle lamp module and lighting device for a motor vehicle

Info

Publication number: CN219036404U
Application number: CN202221796478.6U
Authority: CN
Inventors: D·萨凯特; F·迪南特; E·米德里; F·德贝尔
Original assignee: Valeo Vision SAS
Current assignee: Valeo Vision SAS
Priority date: 2021-07-12
Filing date: 2022-07-12
Publication date: 2023-05-16
Anticipated expiration: 2032-07-12
Also published as: WO2023285384A1; FR3125105A1; CN117836175A; FR3125105B1; EP4370375A1

Abstract

The utility model relates to a lamp module (1) comprising: -a fixed mount (7) intended to serve as a support for the light source (2); -projection optics (3) having a focal plane (F) and designed to project a beam of light of the light emitted by the light source (2); -means (4) for holding the projection optics (3). According to the utility model, the holding means (4) comprises a first support element (41) and a second support element (42). The second support element (42) serves as a support for the projection optics. A first support element (41) connects the second support element to the fixed mount. The support elements (41, 42) are arranged to position the focal plane (F) in: the lamp module ensures good projected image quality despite thermal expansion of the projection optics. The utility model also relates to a lighting device for a motor vehicle.

Description

Motor vehicle lamp module and lighting device for a motor vehicle

Technical Field

The present utility model relates to a lamp module intended to be incorporated into a lighting device for a motor vehicle, and a lighting device for a motor vehicle.

Background

Lighting devices are known to heat up when in use due to the heat released by the light sources present therein. The temperature within the lighting device increases and this may affect the elements contained in this device. For example, it is common for a lens housed in a lighting device to expand with increasing temperature when the lighting device is used to project a beam of light.

Thermal expansion of the lenses may cause a shift in the focal point or focal plane associated with the lenses. When the illumination device is designed to project a pattern, the shifted focal plane is no longer located at the level of the pattern. The projected image thus loses its sharpness. In other words, the quality of the projected image suffers. This phenomenon is also called defocus.

To overcome this problem, lenses are made of glass, a material that is thermally stable and well-tolerated to elevated temperatures. However, these lenses are heavy and expensive. Furthermore, the manufacture of lenses from glass is complex. This is because, when used in a lamp for a motor vehicle, a part of the glass lens is usually made of plastic, which requires over-molding on glass and complicates the manufacturing process.

Another solution proposed is to mount one or more lenses in a support element that is well subjected to high temperatures to prevent lens expansion. In particular, the support element clamps the periphery of the lens or lens group. Thus, the support elements remain fixed despite the temperature rise and apply a load to the lens or lens group such that they cannot expand. However, such loading at the periphery of the lens shifts the deformation caused by thermal expansion to the unloaded zone, in particular the central zone where the optical surface of the lens is located. Thus, the optical surface is deformed more widely than in the case without the support element. Such deformations are difficult to control and may have an uncertain influence on the position of the focal plane.

Disclosure of Invention

In view of the above, it is an object of the present utility model to devise a lamp module intended to be mounted in a lighting device, which reduces or even eliminates the problem of defocusing caused by thermal expansion of the optical elements. Such a lamp module also meets the requirements relating to manufacturing costs and weight while being easy to implement.

In view of this object, the present utility model provides a lamp module including:

-a fixed mount intended to serve as a support for the light source;

-projection optics having a focal plane and being designed to project a beam of light of the light emitted by the light source;

-means for holding projection optics, the means comprising:

a first support element;

a second support element, which serves as a support for the projection optics.

According to the utility model, the second support element is arranged to allow thermal expansion of the projection optics, causing a displacement of the focal plane in the first direction.

Furthermore, the first support element has a first coefficient of thermal expansion and the second support element has a second coefficient of thermal expansion different from the first coefficient of thermal expansion. Finally, the first support element is connected to the fixed mount on one side and to the second support element on the other side such that the second support element is displaced in a second direction opposite to the first direction during deformation of the first support element.

In this case, the fixed mount serves as a reference frame. The fixture mount has little, if any, response to temperature changes in the lamp module. For example, the fixed mount may be made of an inert material that is insensitive to temperature. The second support element carries projection optics. For example, the second support element comprises a recess in which the projection optics are mounted. Finally, the first support element serves as an intermediate portion between the fixed mount and the second support element.

In the proposed lamp module, the projection optics are free to deform by thermal expansion due to the temperature rise within the lamp module. The displacement of the focal plane caused by such deformation is compensated by the holding means.

In particular, the focal plane may be movable within a defined perimeter provided that the holding means does not block expansion of the projection optics. However, the second element of the holding means is designed to orient the displacement of the focal plane in a given direction. In parallel, under the effect of temperature, the holding means also deform to displace the projection optics in a direction opposite to the direction of focal plane displacement.

Thus, despite the displacement caused by thermal expansion of the projection optics, the focal plane is still close to or near the position it was in before the temperature was increased. In other words, the defocus phenomenon is compensated in the proposed lamp module.

Thus, the projected image remains clear throughout to obtain good image quality regardless of the operating time of the lamp module.

Furthermore, since the lamp module is able to compensate for defocusing caused by thermal expansion, it is conceivable to use constituent materials of projection optics that are sensitive to temperature changes but on the other hand inexpensive. For example, the projection optics may be made of Polycarbonate (PC), polymethyl methacrylate (PMMA), cycloolefin polymer (COP), for example under the trademark

Is prepared. However, the proposed holding means are well suited for glass projection optics.

In this document, the projection optics produce a true image of a part of the module (e.g. the source itself or an intermediate image of the source) and possibly a distorted image (scale of at least 30, preferably of the order of 100) at a very large (limited or infinite) distance compared to the size of the module. The projection optics may consist of one or more reflectors, or one or more lenses, or one or more light guides, or even a combination of these possibilities.

The lamp module according to the utility model may optionally have one or more of the following features:

when the temperature changes, the temperature changes from an initial value to a final value, the thermal expansion of the projection optics causes the focal plane to shift a first distance, and the deformation of the first support element causes the second support element to shift a second distance; further, the first coefficient of thermal expansion and the second coefficient of thermal expansion are defined such that the first distance is substantially equal to the second distance; "substantially equal" means that the second distance may be equal to or slightly less than the first distance; thus, the projection optics and focal plane are displaced by approximately the same distance, except for displacement in opposite directions; the shift of each of the projection optics and the focal plane is characterized by a direction and a value as a vector; when the distances are equal, the vector characterizing the projection optics shift and the vector characterizing the focal plane shift are in this case two opposite vectors that cancel each other out; thus, the focal plane remains in a desired position in the lamp module; herein, the "desired position" refers to a position where an image projected by the lamp module has good definition and brightness when the focal plane is located there.

The first support element is in contact with the fixed mount at a first contact zone and with the second support element at a second contact zone, the second contact zone being located on the opposite side to the first contact zone; in other words, the first support element comprises an end portion which is fixed due to its connection to the fixed mount and an end portion which is free due to its connection to the second support element; in this way, when the temperature within the lamp module changes, structural deformation of the first support element occurs at its second contact zone or its free end; herein, "structural deformation" is understood to mean a change in the size of the first support element, including for example its elongation or shortening; furthermore, the first support element is simple in structure, easy to implement, while effectively compensating for the shift of the focal plane of the projection optics;

the first contact zone between the first support element and the fixed mount may comprise at least one portion substantially at the same height as the first face of the projection (projector); thus, the working length in terms of thermal expansion of the first support element is at a maximum; of course, the other portions of the first contact region are not necessarily at the same height as the first side of the projection film;

the projection optics have a first side oriented towards the light source, the second support element supporting the first side of the projection optics;

the projection optics comprise a central region for performing an optical function and a peripheral region surrounding the central region, the second support element being arranged to at least partially conform to the shape of the peripheral region; this allows the second support element to easily grip the projection optics;

the projection optics have a second side on the opposite side to the first side, the second support element comprising an elastically deformable member supported on the second side of the projection optics; thus, in general, the elastically deformable member ensures that the projection optics are properly held by the second support element; in contrast, during a temperature rise, this member deforms so that the projection optics can expand;

the second support element comprises two separate parts;

according to one example, the second projection element comprises a first part and a second part, which are fitted nested in each other to form a receiving space for the projection optics, one of which parts supports the projection optics on a first side of the projection optics and the other part comprises an elastically deformable member supported on the projection optics on a second side opposite to the first side;

for example, the first and second parts are hollow cylinders designed to fit into each other to form a space for receiving projection optics; the first part is intended to support the projection optics at a first end beside the fixed mount, and the second part is partially fitted into the first part; the unassembled portion of the second portion includes an edge folded toward the interior of the projection optical receiving space to form an elastically deformable member; the folded edge is supported at the second end of the projection optics;

alternatively, the second support element is made in one piece; for example, the second support element comprises a hollow cylinder with an annular wall and a flange radially protruding from this wall; the flange is intended to bear against the end of the first support element; the flange may be secured to the first support element by an adhesive layer interposed between the two elements;

-the first support element and the second support element are connected together by adhesive bonding or by snap fastening; for example, the fixing by adhesive bonding includes using a UV-crosslinked adhesive; of course, other securing means are contemplated;

the lamp module comprises a projection sheet arranged upstream of the projection optics in the direction of propagation of the light rays in the lamp module, the projection sheet having a first face which supports the pattern to be projected and is oriented towards the projection optics, and the desired position of the focal plane being on or near said first face; in this application, "near" is understood to mean that the focal plane is located at a distance from the first face such that light rays exiting the light source exit substantially parallel to the optical axis of the projection optics; this distance is for example equal to one tenth of the focal length of the projection optics; therefore, the focal plane is always positioned at and near the first surface of the projection film to ensure the definition of the projection of the pattern;

alternatively, in examples where the lamp module does not have a projection film, the desired position of the focal plane is located at the light source; thus, the projection optics project an image of the light source;

according to an exemplary embodiment, the fixed mount also serves as a support for the projection film; thus, the light source and the projection sheet are positioned in close proximity with respect to each other, thereby simplifying assembly;

-the second coefficient of thermal expansion is smaller than the first coefficient of thermal expansion; in this document, the coefficient of thermal expansion is a negative power of Kelvin (K) ^-1 ) Linear coefficient of thermal expansion in units;

according to one example, the first support element is formed with a thermal expansion coefficient of 90x10 ^-6 K ^-1 And 180x10 ^-6 K ^-1 Between, preferably at 100x10 ^-6 K ^-1 And 150x10 ^-6 K ^-1 The material between them is made;

the first support element is made of polyamide;

the second support element has a thermal expansion coefficient of 12x10 ^-6 K ^-1 And 30x10 ^-6 K ^-1 Between, preferably at 15x10 ^-6 K ^-1 And 24x10 ^-6 K ^-1 The material between them is made;

-the second support element is made of a material selected from aluminium and steel;

-the projection optics has a coefficient of thermal expansion which is larger than the coefficient of thermal expansion of the second support element;

the projection optics comprise a plurality of lenses stacked on top of each other; for example, the number of lenses may be between 2 and 6; optionally, the projection optics comprise four lenses; the four lenses may be made of the same material selected from glass or plastic, or they are a combination of glass lenses and plastic lenses;

the lamp module further comprises a light source and a collimator arranged downstream of the light source in a propagation direction of the light output by the light source, the collimator comprising an upstream face arranged facing the light source and a downstream face arranged facing the projection film; the light beam leaving the collimator is thus constituted by parallel rays directed in the direction of the projection optics; the collimator may thus limit scattering of light emitted by the light source;

when the lamp module is incorporated in a lighting device, the fixed mount is connected to the housing of this device.

Another subject of the utility model is a motor vehicle lighting device comprising a lamp module according to the utility model.

For example, the lighting device provides an auxiliary function of illuminating a space located on both sides of the vehicle.

According to one embodiment, a lighting device includes a housing. The fixed mount is connected to the housing by suitable fixing means.

Drawings

Further innovative features and advantages will become apparent from the following description, given by way of non-limiting indication, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a side view of a motor vehicle including a lamp module according to one exemplary embodiment of the present utility model;

FIG. 2 shows a cross-sectional view of the lamp module of FIG. 1;

FIG. 3 shows a detailed cross-sectional view of the lamp module of FIG. 1;

FIG. 4 shows an exploded view of the lamp module illustrated in FIG. 3;

FIG. 5A shows a schematic illustration of a lamp module at ambient temperature T0;

fig. 5B shows a schematic illustration of the lamp module at a first temperature T1, which is higher than the ambient temperature.

Detailed Description

Referring to these figures, and in particular to fig. 1, a motor vehicle 10 includes a front door 11 and a rear door 13 on the left side of the illustration. The lighting device with the lamp module 1 (not visible in fig. 1) is mounted in a door sill 12 located below a front door 11 and a rear door 13. In the illustrated example, the lighting device is located at the front end of the rocker 12 and is designed to project an illumination field S onto the ground, which extends parallel to the main axis P of the vehicle 10 and as far as the rear of the vehicle 10. The projection axis forms an angle alpha with the horizontal axis.

The lighting device serves as a side lighting device for the space beside the front door and the rear door.

In fig. 2, the lamp module 1 comprises a light source 2, projection optics 3 and a projector sheet 5 arranged between the light source 2 and the projection optics 3.

The light source 2 is in this case an LED ("light emitting diode" abbreviation). Other types of light sources are conceivable. The light source 2 may comprise one or more LEDs.

In the example shown, the projection optics 3 has a focal plane F and is composed of a plurality of lenses 30, which are stacked on top of one another. There are four lenses.

Each lens 30 comprises a central zone 311 having a refractive surface that performs an optical function and a peripheral zone 312 surrounding the central zone 311. The refractive surface is configured to project light output by the light source 2 while limiting optical aberrations such as aberrations. The projection optics 3 are hereinafter referred to as lens group 3.

The peripheral region 312 is provided with engagement means intended to cooperate with complementary engagement means in the peripheral region of an adjacent lens. For example, the engagement means may comprise grooves or ribs.

The slide 5 is in this case a transparent plate 53, which illustratively has a square cross section. The slide 5 may be made of glass, such as borosilicate glass, or of plastic, such as polyethylene terephthalate (PET).

The slide 5 has a first face 51 and a second face 52. The projector is placed in the lamp module 1 such that the first face 51 is oriented towards the lens group 3 and the second face 52 is oriented towards the light source 2. The first face 51 is also referred to as a downstream face and the second face 52 is also referred to as an upstream face. The terms "upstream" and "downstream" are defined along the direction of light propagation in the lamp module 1.

Fig. 3 and 4 illustrate the lamp module 1 in more detail, showing additional elements of the lamp module 1, in particular the holding member 4 and the fixed mount 7.

In the illustrated example, the fixed mount 7 serves as a support for the light source 2 and the projector sheet 5. In this case, the fixed mount 7 comprises a base 20 on which the light source 2 is mounted. The base 20 may be a printed circuit board (or PCB).

The fixed mount further comprises a frame 50 carrying the projector 5 and a collimator 6 placed between the light source 2 and the projector 5. In this case, the collimator 6 is an integral part of the frame 50. The collimator 6 comprises an upstream face 61 arranged facing the light source 2 and a downstream face 62 arranged facing the projector 5.

In this example, the frame 50 is fixed to the base 20 by two fixing protrusions 51 and two pins 52. Specifically, the fixing tab 51 abuts the minor face 22 of the base 20, while the pin 52 engages in a corresponding hole formed in the base 20. In this way, the base 20 and the frame 50 form a block constituting the fixed mount 7.

The projection optics 3 are connected to the fixed mount 7 by means of the holding means 4. In this case, the holding means 4 serves both as a support for the lens 30 and as a means of positioning the lens relative to the slide 5.

According to the utility model and as illustrated example, the holding means 4 comprise a first support element 41 and a second support element 42.

The first support element 41 is an intermediate portion connecting the fixed mount 7 to the second support element 42. In particular, the first support element 41 is formed in this case by a cylindrical sleeve interposed between the fixed mount 7 and the second support element 42. The first support element is also referred to as a cartridge in the words of the person skilled in the art. The first support element 41 comprises an engagement protrusion 413 intended to be inserted into a groove 513 formed in the fixed mount 7 in order to assemble the two elements.

Once assembled, the first support element 41 is in contact with the fixed mount 7 at its first end 411 oriented towards the fixed mount 7. The first end 411 is also referred to as a first contact area 411.

In this case, the first contact area 411 includes a plurality of contact portions. Some of which are located at the same level as the first face 51 of the projector blade 5. Other contact portions are located at a higher level than the projection sheet, in particular contact portions between the first support element 41 and the shoulder of the fixing projection 51 of the frame 50. In other words, the connection between the first contact area 411 and the first face 51 may be realized at different heights.

In the illustrated example, the first support element 41 is connected to the second support element 42 at a second end 412 thereof, which is located at an opposite end from the first end 411. In this case, the first support element 41 is in contact with the second support element 42 by means of an adhesive layer, which connects the two elements together. Other means of connection are contemplated. Bonding the first support element 41 and the second support element 42 together by adhesive bonding makes it possible to easily adjust the position of the focal plane F of the lens group 3 with respect to the projection film 5.

In this case, the second support element 42 comprises two separate parts which are nested in each other to form a receiving space for the lens group 3. The second support element 42 is also referred to as a lens box.

Specifically, the first portion 421 includes a hollow cylinder open on both sides. However, the opening on one side is smaller than the opening on the other side. Specifically, a first side (the side oriented toward the light source) of the first portion 421 includes an inwardly folded edge to form an annular seat 423. In this case, the shape of the annular seat 423 is complementary to the shape of the peripheral zone 312 of the lens 30 in direct contact with this seat. In this way, the annular seat 423 perfectly conforms to the shape of the peripheral zone 312, ensuring a correct retention between the first portion 421 and the lens 30. The annular seat 423 defines a first opening 425 having a diameter corresponding to the diameter of the central region 311 of the lens 30.

The second side of the first portion 421 (the side opposite the first side) includes a flange 424 that is disposed on the second end 412 of the first support element 41 and secured thereto by suitable means, such as a UV-crosslinkable adhesive, a thermal adhesive, or a combination of both types of adhesives. The flange 424 defines a second opening 426 having a diameter greater than the diameter of the first opening 425. The second opening 426 is intended to be wide enough to receive the second portion 422 of the second support member 42.

In this case, the second portion 422 also comprises an open ended hollow cylinder. The second portion 422 is partially assembled in the first portion 421. The free end (the non-assembled end) of the second portion 422 includes an inwardly folded edge 428 that is supported on the diaphragm 33. The membrane is part of the lens group 3 and comprises an opening defining the optical surface of the lens group 3.

The second portion 422 is designed such that the folded edge 428 exhibits an elastic deformation behavior, which means that the edge 428 tends to return to its original position when it is deformed. In this case, the thickness of the second portion 422 is small enough to impart elastic behavior to the edge 428. Edge 428 is shown in its original position when it is supported on diaphragm 33 in fig. 3. This bearing contact is in addition to the contact of the annular seat 423 with the lens group 3 on the other side in order to clamp this group 3 by eliminating the gap between the lenses 30.

The second portion 422 designed in this way is also referred to as an elastically deformable member. In addition, the elastic deformation of the edge 428 allows the lens group 3 to expand when the temperature of the lamp module increases. Specifically, as lens group 3 expands, edge 428 is raised by the pushing action of the lens group.

Once the first and

second portions

421 and 422 are assembled, the two portions form a housing that houses the lens group 3. The housing constitutes a second support element 42.

In the illustrated example, each of the lens group 3, the first support element 41, and the second support element 42 expands upon a temperature change. In this case, each of these elements is made of a material having a positive thermal expansion coefficient, which means that when the temperature increases, these elements expand and their size increases. However, the coefficients of thermal expansion of these elements are different in order to help limit defocusing of the projection optics, in particular by the above-described assembly. In other words, the arrangement of the above-described lamp module and the different composition of certain elements in this lamp module are such that the focal plane F can be kept at a desired position despite the temperature rise in the module, in this case substantially at the first face 51 of the projector blade 5.

The operating principle of the proposed concept will now be explained in detail with reference to fig. 5A and 5B.

FIG. 5A illustrates at ambient temperature T ₀ And fig. 5B illustrates the lamp module 1 at a temperature above ambient temperature T ₀ Temperature T of (2) ₁ Is provided. As can be seen from these figures, the lens group 3, the first support element 41 and the second support element 42 are at a temperature T from the ambient temperature ₀ Travel to higher temperature T ₁ While changing their size and/or position, while the focal plane F remains in the same position in both cases.

In the illustrated example, the first support element 41 is made of a material having a first coefficient of thermal expansion α1. The second support element 42 is made of a material having a second coefficient of thermal expansion α2. The lens group 3 has a third coefficient of thermal expansion α3. In this case, these coefficients are classified in descending order of their values as follows:

-a first coefficient of thermal expansion α1;

-a third coefficient of thermal expansion α3; and

-a second coefficient of thermal expansion α2.

If the holding means 4 is not present, expansion of the lens group 3 caused by a temperature rise in the module will displace the focal plane F in the direction of the arrow D illustrated in fig. 5A towards the fixed mount 7 until the position of the focal plane F' illustrated in fig. 5A at temperature T1 is reached. Note that the final position of the focal plane F caused by the expansion of the lens group 3 without the holding means 4 is depicted in fig. 5A for ease of understanding and at ambient temperature T ₀ The situation in fig. 5A below is irrelevant.

The distance the focal plane F is shifted (referred to as the second distance d 2) depends on the change in temperature:

d2＝f(ΔT)

wherein in this case: Δt=t1-T0.

In the illustrated example lamp module, when the temperature increases, the lens group 3 provided in the holding member 4 expands in a direction away from the fixed mount 7, as indicated by an arrow C illustrated in fig. 5B. Such expansion is possible by means of the configuration of the second support element 42 with the elastically deformable member 422 described above. Furthermore, since the coefficient of thermal expansion α2 of the second support element 42 is smaller than the coefficient of thermal expansion (α3) of the lens group 3, the second support element expands the group 3 more in one direction than in the other direction. In this case, group 3 expands more on the side of the second portion 422 than on the side of the first portion. In addition, when the temperature drops, the second support member 42 contracts more than the lens group 3 to ensure that the lens group 3 is properly clamped.

The expansion of the lens group 3 causes the focal plane F to shift. In practice and as a non-limiting example, the displacement of the focal plane F at a given temperature variation is calculated by thermo-optical simulation using the bearing surface between the first support element and the fixed mount as a reference point. This calculation may be performed for each point within the operating temperature range.

With knowledge of the behaviour of the lens group 3 and the displacement of the focal plane, the first support element 41 and the second support element 42 are designed to position the focal plane F at the first face 51 of the projection sheet in spite of the expansion. Specifically, the difference between the coefficient of thermal expansion (α1) of the first support element 41 and the coefficient of thermal expansion (α2) of the second support element 42 needs to be large enough to displace the lens group 3 in the direction opposite to the focal plane F displacement and by a distance substantially equal to the focal plane F displacement.

Specifically, when the temperature rises to a value T ₁ When the first support element 41 is elongated in a direction away from the fixed mount 7, as indicated by arrow a in fig. 5B. The length of the first support element 41 is from ambient temperature T ₀ Initial value L below ₀ Becomes the temperature T ₁ Lower higher value L ₁ 。

In parallel, the second support element 42 is elongated in the direction of the fixed mount 7, as indicated by arrow B. In this case, the first portion 421 is elongated towards the fixed mount 7, since the other end of the first portion is connected to the first support element 41. The elongation of the second support element 42 reflects the expansion of the lens package 3. The second support element 42 has an intermediate effect allowing both the expansion of the group 3 and the displacement by deformation of the first support element. This displacement causes the lens group 3 to move in a direction opposite to the movement of the focal plane F. The value of the displacement distance depends on the coefficients of thermal expansion of the first support element 41 and the second support element 42.

Specifically, due to the deformations of the first support element 41 and the second support element 42, the lens group 3 is displaced a first distance d1 in the direction away from the fixed mount 7 indicated by arrow E. This distance depends on the elongation of each of the first support element 41 and the second support element 42 and their respective coefficients of thermal expansion:

d1＝(α1-α2)x L0 xΔT

wherein in this case: l (L) ₀ : an initial length of the first support element 41;

ΔT＝T1-T0。

the focal plane F associated with the lens group 3 is displaced in the same way as this group, that is to say in a direction away from the fixed mount 7 and by a value of the first distance d1.

Therefore, in order to position the focal plane F relatively close to the initial position, or even at the same position as before the temperature rise, the lens group 3 needs to be raised to compensate for the displacement of the focal plane F caused by the expansion phenomenon.

In other words, the first distance d1 and the second distance d2 need to be substantially equal, except that the lens group 3 and the focal plane F are shifted in opposite directions: d1 =d2 (+/-10%). This is obtained by appropriately selecting the first thermal expansion coefficient α1 and the second thermal expansion coefficient α2.

The results obtained are illustrated in fig. 5B. The elevation of the lens group 3 causes the focal plane F' to rise to a position F "which is at the same position as the focal plane F at ambient temperature. Of course, the position F "may not be exactly at the initial position, but in this case it is close to this initial position to ensure that the quality of the image projected by the lamp module is good.

Thus, the lamp module 1 described above solves the problem of defocusing encountered when the temperature within the module increases. Since the focal plane remains on the first side of the projector sheet, the projection of the pattern is clearly displayed during use of the module, irrespective of the duration.

Claims

1. A lamp module (1), the lamp module comprising:

-a fixed mount (7) intended to serve as a support for the light source (2);

-projection optics (3) having a focal plane (F) and designed to project a beam of light of the light emitted by the light source (2);

-means (4) for holding the projection optics (3), comprising:

-a first support element (41);

-a second support element (42) serving as a support for the projection optics; the method is characterized in that:

-the second support element (42) is arranged to allow thermal expansion of the projection optics (3), causing a displacement of the focal plane (F) in a first direction (D);

-the first support element (41) has a first coefficient of thermal expansion (a 1), the second support element having a second coefficient of thermal expansion (a 2) different from the first coefficient of thermal expansion; and is also provided with

-the first support element (41) is connected on one side to the fixed mount (7) and on the other side to the second support element (42) so as to displace the second support element (42) in a second direction (C) opposite to the first direction (D) during deformation of the first support element (41).

2. The lamp module of claim 1, wherein:

-when the temperature changes from an initial value (T0) to a final value (T1):

■ The thermal expansion of the projection optics (3) causes the focal plane (F) to be displaced by a first distance (d 1), and

■ -deformation of the first support element (41) displaces the second support element by a second distance (d 2); and wherein the first coefficient of thermal expansion (α1) and the second coefficient of thermal expansion (α2) are defined such that the first distance (d 1) is substantially equal to the second distance (d 2).

3. A lamp module according to claim 1, characterized in that the second coefficient of thermal expansion (a 2) is smaller than the first coefficient of thermal expansion (a 1).

4. A lamp module according to claim 2, characterized in that the second coefficient of thermal expansion (a 2) is smaller than the first coefficient of thermal expansion (a 1).

5. A lamp module according to claim 1, characterized in that the first support element (41) is in contact with the mount (7) at a first contact zone (411) and in contact with the second support element (42) at a second contact zone (412), which is located on the opposite side to the first contact zone (411).

6. The lamp module (1) according to any one of claims 1 to 5, wherein the projection optics (3) has a first side (31) oriented towards the light source (2), the second support element (42) supporting the first side (31) of the projection optics (3).

7. The lamp module (1) according to claim 6, characterized in that the projection optics (3) comprise a central region (311) which fulfills an optical function and a peripheral region (312) surrounding the central region (311), the second support element (42) being arranged to at least partially conform to the shape of the peripheral region (312).

8. The lamp module (1) according to claim 6, characterized in that the projection optics (3) have a second side (32) on the opposite side to the first side (31), the second support element (42) comprising an elastically deformable member bearing on the second side (32) of the projection optics.

9. The lamp module (1) according to claim 7, characterized in that the projection optics (3) have a second side (32) on the opposite side to the first side (31), the second support element (42) comprising an elastically deformable member bearing on the second side (32) of the projection optics.

10. The lamp module (1) according to any one of claims 1 to 5, 7 to 9, wherein the second support element (42) comprises two separate parts (421, 422).

11. The lamp module (1) according to claim 10, characterized in that the second support element (42) comprises a first portion (421) and a second portion (422), which are fitted nested in each other to form an accommodation space for the projection optics (3), one of which portions supports the projection optics on a first side (31) of the projection optics and the other portion comprises an elastically deformable member supported on the projection optics on a second side (32) opposite to the first side (31).

12. A lamp module (1) according to claim 6, characterized in that the second support element (42) comprises two separate parts (421, 422).

13. The lamp module (1) according to claim 12, characterized in that the second support element (42) comprises a first portion (421) and a second portion (422), which are fitted nested in each other to form an accommodation space for the projection optics (3), one of which portions supports the projection optics on a first side (31) of the projection optics and the other portion comprises an elastically deformable member supported on the projection optics on a second side (32) opposite to the first side (31).

14. The lamp module (1) according to any one of claims 1 to 5, 7 to 9, 11 to 13, characterized in that the second support element (42) is made in one piece.

15. The lamp module (1) according to claim 6, characterized in that the second support element (42) is made in one piece.

16. The lamp module (1) according to claim 10, characterized in that the second support element (42) is made in one piece.

17. The lamp module (1) according to any one of claims 1 to 5, 7 to 9, 11 to 13, and 15 to 16, characterized in that the first and second support elements (41, 42) are connected together by adhesive bonding or by snap fastening.

18. A lamp module (1) according to claim 6, characterized in that the first and second support elements (41, 42) are connected together by adhesive bonding or by snap fastening.

19. A lamp module (1) according to claim 10, characterized in that the first and second support elements (41, 42) are connected together by adhesive bonding or by snap fastening.

20. A lamp module (1) according to claim 14, characterized in that the first and second support elements (41, 42) are connected together by adhesive bonding or by snap fastening.

21. The lamp module (1) according to one of claims 1 to 5, 7 to 9, 11 to 13, and 15 to 16, characterized in that the lamp module comprises a projection sheet (5) arranged upstream of the projection optics (3) in the direction of light propagation in the lamp module, the projection sheet having a first face (51) which supports the pattern to be projected and is oriented towards the projection optics, and the desired position of the focal plane (F) is on or near the first face.

22. The lamp module (1) according to claim 21, wherein the fixed mount (7) also serves as a support for the projector sheet (5).

23. The lamp module (1) according to any one of claims 1 to 5, 7 to 9, 11 to 13, and 15 to 16, characterized in that the projection optics (3) comprises a plurality of lenses (30) stacked on top of each other.

24. Lighting device for a motor vehicle, characterized in that it comprises a lamp module according to one of the preceding claims.

25. A lighting device as claimed in the preceding claim, characterized in that the lighting device comprises a housing and that a fixed mount (7) of the lamp module (1) is connected to the housing.